From the picture we notice that the angles R and Q are the same. Furthermore the interior angle S of the triangle is:
[tex]180-(8x+4)[/tex]Then we have the equation:
[tex]2(5x-4)+180-(8x+4)=180[/tex]Solving for x we have:
[tex]\begin{gathered} 10x-8-8x-4=0 \\ 2x-12=0 \\ x=6 \end{gathered}[/tex]Now we plug the value of x in the expression for the angle RST, then:
[tex]8(6)+4=52[/tex]Therefore the angle RST is 52°.